The present invention relates to a deformation structure, in particular for a pedestrian protection for a motor vehicle. The deformation structure is adapted, for example, to be arranged between a bumper covering and a bumper transverse support.
A known front end of a motor vehicle, for example, has a bumper transverse support, which is fastened to forward ends of longitudinal supports, and a bumper covering. A soft foam, which can be deformed at a comparatively low load level, is arranged between the bumper covering and the bumper transverse support, for the protection of pedestrians. As a result of a pedestrian protection, the soft foam is arranged, as the circumstances require, for protecting a pedestrian from a direct collision with a hard rigid structure of the motor vehicle, for example, the bumper transverse support.
Furthermore, there is a requirement that, at a very low speed range of up to, for example, 4 km/h, in which pedestrian protection is not relevant because of the low speed, the motor vehicle will not be damaged in the event of a collision.
In addition, at a slightly higher speed, which still is also not relevant to pedestrian protection, there is the requirement that damage in the event of a collision be as minor as possible and that, for example, a radiator structure, which is situated in the front end region, not be damaged.
The various requirements partly conflict with one another and require a comparatively long vehicle overhang at the vehicle front and therefore have higher weight and a disadvantageous influence on the driving dynamics.
For solving the conflicting objectives arising therefrom, a bumper arrangement having a transverse support was suggested in German Patent document DE 102010054641 A1, which is fastened to the vehicle body by way of crash boxes. A pedestrian protection element for a soft impact of a pedestrian is constructed in the driving direction in front of the transverse support. In addition, a swivelable energy absorption element is provided, which can be swiveled in front of the pedestrian protection element and thereby permits an increased energy absorption in the event of collisions in which a higher collision energy absorption capacity of the crash structure of the motor vehicle is required.
German Patent document DE 102012112636 A1 also shows a bumper arrangement having a bumper transverse support and a pedestrian protection element, which can be switched by way of an actuator from a rigid state to a comparatively soft state, which serves a pedestrian protection.
German Patent documents DE 102010054641 A1 and DE 102012112636 A1 have in common that a crash or pre-crash sensor system is required, in which case, on the basis of the output signals of the sensor system, a switching-over can take place between a hard rigid state of the crash structure with a high collision energy absorption capacity and a soft state of the crash structure with a lower collision absorption capacity for the benefit of pedestrian protection.
It is therefore an object of the present invention to create a deformation structure, particularly for the pedestrian protection for a motor vehicle, which is adapted, for example, for arrangement between a bumper covering and a bumper transverse support, and which, as a function of a load event, can be deformed at different energy levels, has a simple construction and functions independently of a sensor system and an actuator respectively.
This and other objects are achieved by a deformation structure in accordance with embodiments of the invention.
A deformation structure, which may also be called an energy absorption structure, has a row of deformation elements arranged in a deformation direction, i.e. the direction of a load action, behind one another. In each case, two mutually adjoining deformation elements are mutually coupled by a coupling mechanism such that, in a first load event, particularly a first collision load event, two adjoining deformation elements will enter into a mutually latching engagement or are in a latching engagement, so that a relative displacement of the adjoining deformation elements with respect to one another in the deformation direction is prevented or at least made more difficult and a deforming of the deformation structure takes place at a high force level. And, in a second load event, particularly a second collision load event, two adjoining deformation elements do not enter into the latching engagement or leave the latching engagement, so that a relative displacement of the adjoining deformation elements in the deformation direction is made possible or at least facilitated, and a deforming of the deformation structure takes place at a low force level.
As a result of the deformation structure according to the invention, no collision sensor system and no actuator system are required in order to possibly actively lock or unlock a mechanical mechanism and thereby to be able to change over, as required, between a structure with a “soft” deformation behavior and a “rigid” deformation behavior. The deformation structure can thereby achieve the above-mentioned object by use of simple devices, while utilizing a latching engagement of the coupling mechanism which, as a function of a load event, engages or does not engage or remains in the engaged condition or moves out of this engaged condition, between adjoining deformation elements. In this case, the coupling mechanism utilizes a mass inertia of the latching elements for the latching engagement, which mass inertia leads or does not lead to a latching engagement at different deformation speeds, thus a speed of a displacement of two adjoining deformation elements with respect to one another.
The deformation structure is designed and can be used, for example, for the pedestrian protection for a motor vehicle. In particular, the deformation structure may be adapted for the arrangement in a region between a bumper covering, which forms a vehicle skin, and a bumper transverse support.
In particular, the deformation direction is a collision direction and, when used for the pedestrian protection in the motor vehicle front or the motor vehicle rear, is a longitudinal direction of the vehicle. A relative displacement between adjoining deformation elements takes place essentially in the longitudinal direction of the motor vehicle, which normally also is a main direction in the case of a frontal collision of the motor vehicle. In this case, the coupling mechanism according to the present invention acts independently of a collision sensor system autonomously, for example, by a utilization of the mass inertia of the latching engagement.
However, basically, the protection range of the deformation structure according to the invention also extends to all other application ranges in the motor vehicle field or other fields of technology, in which a deformability of a deformation structure is required at different load levels as a function of a load event.
According to a preferred further development of the deformation structure, each deformation element, as a component of the coupling mechanism, has an elastically deformable element. The elastically deformable element engages with the adjoining deformation element and, in the first load event, is in the latching engagement with the adjoining deformation element, or enters into the latching engagement with the adjoining deformation element and, in the second load event, does not enter into the latching engagement with the adjoining deformation element or leaves the latching engagement of the adjoining deformation element.
The deformation element may also have more than one elastically deformable element, for example two, three or four or more elastically deformable elements.
In the case of the deformation structure having the elastic element, the coupling mechanism may preferably be designed such that the elastically deformable element can be elastically deformed and thereby prestressed by a relative displacement of two adjoining deformation elements.
This has the advantage that a prestressing of the elastically deformable element does not take place before the load event and, in a normal condition, the deformable element is relaxed, and thereby the function of the deformation structure can be better ensured for a long period of time. A loss of a prestressing force over the long time period is thereby avoided.
As an alternative, the elastically deformable element can already be prestressed in the normal condition without a load event.
This has the advantage that no relative displacement between the deformation elements is required for the prestressing, and the deformation structure may possibly have a shorter construction.
Furthermore, the coupling mechanism may, in particular, be designed such that, while utilizing a mass inertia of the prestressed elastically deformable element, at a first, for example, lower displacement speed, the elastically deformable element of the one deformation element enters into an indentation of the other deformation element in the latching engagement, and the elastically deformable element, at a second, for example, higher displacement speed, does not enter into the latching engagement with the indentation. As an alternative, the elastically deformable element may also engage with a projection of the adjoining deformation element. An automatic mechanism is thereby created, which utilizes a mass inertia of the elastically deformable element for its function. As a result, an engagement takes place at a low displacement speed and therefore a low collision speed, and the deformation element therefore acts in a rigid manner. At the fast displacement speed and therefore the fast collision speed, the elastically deformable element does not engage, and a further displacement becomes possible between the adjoining deformation elements, whereby the deformation structure as a whole reacts in a soft manner.
The latching engagement can therefore establish a form-locking connection between the adjoining deformation elements, so that a relative displacement between the adjoining deformation elements is no longer possible, and the adjoining deformation elements therefore have a “rigid” behavior.
According to a preferred embodiment, the elastically deformable element of a deformation element can be designed to be interacting with an adjoining deformation element such that, with a displacement of the adjoining deformation elements with respect to one another, the elastically deformable element can be elastically deformed and prestressed, for example, by way of a slanting contact surface of the adjoining deformation element.
As a result, it becomes possible to generate the prestressing of the elastically deformable element during the load event. In other words, for example, a collision load can be utilized for a prestressing of the elastically deformable element.
The elastically deformable element may be a leg whose forward, for example, free end has a detent projection or a detent indentation for a latching engagement with the adjoining deformation element, and whose rearward end, similar to a cantilever, is fixedly clamped in, so that the forward end with the detent can have a spring effect. The leg may have a flat, thus a leaf-shaped construction and can therefore act like a leaf spring. During the rapid displacement, the detent or detent indentation slides particularly over and beyond the counterpart of the adjoining deformation element, and a further displacement between the adjoining deformation elements is made possible, whereby the deformation structure as a whole reacts in a soft manner.
The deformation elements may essentially be designed in a U-shape with a base element and two opposite legs, which each form the elastic element, wherein ends with, for example, a detent or detent indentation of the legs are coupled with the base element of a further deformation element.
In particular, the two legs may be arranged symmetrically with respect to one another. Furthermore, the two legs may be deformable or prestressable in opposite directions.
According to an advantageous further development, in the case of a deformation structure of the present invention, each deformation element may be constructed in one piece.
As a result, the production of the deformation elements and of the deformation structure is simplified, and the number of components is small.
According to a further advantageous development, the deformation elements may be constructed of a plastic material.
A plastic material has a light weight, can be produced in a cost-effective manner and, in a particularly simple fashion, can be used for constructing a coupling mechanism having a latching engagement.
According to a further development of the deformation structure, a plurality of rows of deformation elements are arranged side-by-side.
The term “side-by-side” particularly means adjacent to one another and also includes the “above-one-another” arrangement.
When applied to the case of the pedestrian protection in a motor vehicle, this means that the rows of deformation elements may be arranged side-by-side in the y- and/or z-direction. In particular, the deformation structure with the plurality of rows of deformation elements may essentially fill a space between the bumper covering and the bumper transverse support relevant to a pedestrian protection. In the case of a local stressing of the deformation structure, a corresponding local deforming of the deformation structure may take place.
Particularly when used for the pedestrian protection of a motor vehicle, a row of deformation elements may, for example, be constructed of three to fifteen, for example, ten deformation elements arranged behind one another. Depending on the installation space and the use case, rows that are arranged side-by-side may have a different number of deformation elements.
According to a further development of the deformation structure with several adjacent rows of deformation elements, deformation elements that are arranged directly side-by-side may be mutually connected by means of a web.
The deformation structure can thereby form an integral modular unit, which can easily be handled, for example, mounted. Furthermore, such a deformation structure can, for example, easily be produced as a component by so-called rapid prototyping or rapid manufacturing, for example, laser sintering or stereo-lithography.
In particular, the web may be constructed such that, in the collision load event, it will fail in a brittle and/or plastic manner. Specifically, the web will fail without impairing a function of the mutually adjoining deformation elements.
The web therefore does not have any effect on a function of the deformation structure and particularly of the coupling mechanism.
According to a preferred further development of the deformation structure, the deformation elements are adapted such that, in a latching engagement state, i.e. in the first load event, in which the deformation structure is more rigid, they absorb energy by plastic deformation and/or brittle failure of the deformation elements over a predefined deformation distance.
Preferably, an energy absorption capacity of the deformation elements, which are in a latching engagement or remain in the latching engagement, is greater than an energy absorption capacity of the deformation elements which do not enter in the latching engagement or leave the latching engagement.
According to a further development of the deformation structure, the deformation elements may have identical constructions.
According to a preferred further development, in the use case of the deformation structure as a pedestrian protection in the motor vehicle, below a collision speed threshold value, the row of deformation elements reacts in a more rigid manner as a result of the latching of adjoining deformation elements and, when the collision speed threshold value is reached, reacts in a softer manner as a result of the release or the absence of the latching.
The structure of the front end or of the rear end of the motor vehicle can therefore be constructed to be sufficiently rigid for a relatively low speed, so that no structural damage, for example, of the bumper covering or the like will occur as a result of excessive deforming. Repair costs can thereby be minimized in the event of collisions at a very low speed, for example, in the case of so-called trivial damage when parking and can be limited merely to the touching-up, for example, of paint damage.
Above the collision speed threshold value that is relevant to a pedestrian protection, no latching of adjoining deformation elements takes place, and the row of deformation elements can be changed in its length at a relatively low force for the protection of pedestrians, i.e. can be pushed together by the relative displacement of the adjoining deformation elements with respect to one another.
Depending on the collision load and therefore the speed during the collision, the deformation structure can therefore react completely rigidly and transmit the collision load to the crash structure of the vehicle situated behind it, or a load threshold value of the latched deformation elements is exceeded and the row of deformation elements fails as a result of brittle fracture or plastic deforming and can therefore absorb collision energy for the protection of other components and of the vehicle occupants.
In the use case of the deformation structure as pedestrian protection in the motor vehicle, a row of deformation elements may have a length of from 50 to 150 mm. The row of deformation elements may preferably have a length of between 70 and 110 mm. In the second load event, the row of deformation elements may preferably be deformable at a low force level by 60 to 110 mm.
The above-mentioned further developments of the invention may be arbitrarily combined with one another to the extent possible and meaningful.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.